This is a multi-disciplinary attack on the mechanism of olfactory communication in animals with emphasis on the stimulus response pheromone action. The project employs gas chromatography, neuroanatomical, electrophysiological and behavioral techniques. The following problems are under investigation: 1. Analysis of biological odors, 2. receptor function, 3. neural coding, 4. neuroanatomy of the olfactory system, 5. sex behavior, and 6. social behavior in hamsters and scent marking in the gerbil. In addition, attention will be given to the possible role of the vomeronasal organ and the accessory olfactory bulb in these behaviors.